1. Technical Field
The present disclosure generally relates to advantageous systems and methods that offer vapor barrier properties to porous structures, e.g., concrete structures. The disclosed systems and methods utilize water soluble materials that may be incorporated into the porous structure, e.g., concrete structure, at various points in time, e.g., at the pre-hardening stage, the post-hardened stage, or combinations thereof.
2. Description of Background Art
The cost of corrosion and other structural defects in materials is devastating with respect to damage and deterioration to structures as well as the potential for human injury. From a financial perspective, the cost of corrosion alone is estimated to be over $300 billion each year in the United States. The problem of preventing corrosion and addressing other potential structural defects remains a challenge confronting the construction and maintenance industries.
Commonly, structures are made of concrete materials. Because conventional concrete has very low tensile strength, it is common practice to reinforce concrete with steel bars in applications where the concrete is subjected to substantial loads. In such implementations, the concrete has at least two functions. One function is to protect the reinforcing steel bars against corrosion. Another prominent function is to improve resistance from shear and compressive stresses. As a general matter, the protective effect of hardened concrete against climatic and environmental conditions on reinforcing steel depends, for example, on the amount and type of cement, water/cement factor and concrete integrity. However, since concrete is also a permeable absorptive material, concrete is often subject to undesirable intrusion of moisture and other substances, each of which can lead to corrosion of the reinforcing steel.
Indeed, concrete is widely known to be a porous material with a vast network of interconnected pores. When the pores of concrete are occupied by water and the relative humidity of the ambient atmosphere is unsaturated, moisture vapor will be emitted from the concrete. In many circumstances, the moisture vapor emissions from concrete simply become part of the humidity of the air. However, in some circumstances, especially involving concrete slabs that accommodate flooring overlay materials, the moisture vapor emission from the concrete causes negative consequences, such as degradation of the flooring glue and delamination of the flooring material. For at least the foregoing reasons, it is advantageous to reduce or eliminate the moisture vapor emission from concrete.
There are numerous methods in practice for reducing moisture vapor emission from concrete systems. Particular methods are frequently employed based at least in part on the source of the moisture-at-issue. In the case of free mix water or surface rain water potentially emerging from a concrete structure/system, various sealant systems and drying techniques have been used to reduce the rate of moisture vapor emission to acceptable levels. These methods are expensive and labor intensive to apply. In the case of groundwater wicking through a concrete slab and emerging as moisture vapor, various polymer sheet vapor barriers have been used to prevent or reduce the degree to which the groundwater contacts the concrete and wicks therethrough. Such sheets involve additional cost/labor and are susceptible to various levels of unreliability due to seams and punctures.
It is noted that efforts have been made to solve the premature deterioration of concrete structures. For example, U.S. Pat. No. 4,869,752 to Jaklin describes the use of modified inorganic silicates, e.g., modified alkali silicates, as a concrete additive to prevent corrosion of steel structures or reinforcing steel. U.S. Pat. No. 6,277,450 to Katoot describes the use of a coating process to coat metal surfaces which are modified to an active moiety of metal hydroxide receptive to a fully cross-linked polymer of various thickness. Other processes that have been used have included precoating surfaces of metals used in the building and construction industry. However, such methods are generally costly, ineffective and inefficient/impractical.
In commonly assigned applications, materials and systems for treatment of concrete structures have been disclosed. U.S. Patent Publication No. 2004/0237834 to Humphrey et al. discloses a composition for concrete treatment and a method for synthesis thereof. The disclosed composition is an alkali-based salt solution of a dioic acid of the following chemical formula:
wherein M+ is selected from the group comprising Na+ and K+; R1 is a C1 to C24 branch or linear aliphatic compound; and R2 is a C1 to C10 branch or linear aliphatic compound.
U.S. Patent Publication No. 2004/0237835 to Rhodes et al. discloses a further concrete treatment system that includes the alkali-based salt solution of a dioic acid of the Humphrey et al. patent publication (U.S. Patent Publication No. 2004/0237834) in combination with a defoaming agent, e.g., a polyether modified polysilixane, tri-alkane/alkene phosphates and mixtures thereof. The disclosed defoaming agent is effective in reducing excessive air entrainment and/or foaming during preparation of concrete mixes and in controlling air content of the cured concrete.
Reference is also made to a pair of publications by Mark Allyn, Jr. and Gregory C. Frantz. In a first publication, Allyn, Jr., et al. describe strength and durability testing of concrete containing salts of alkenyl-succinic acid, specifically disodium tetrapropenyl succinate (DSS) and diammonium tetrapropenyl succinate (DAS). [Allyn, Jr., et al., “Strength and Durability of Concrete Containing Salts of Alkenyl-Succinic Acid,” ACI Materials Journal, January-February 2001, pages 52-58]. In a second publication, Allyn, Jr., et al. describe corrosion testing of the foregoing materials over a 48 week period. [Allyn, Jr., et al., “Corrosion Tests with Concrete Containing Salts of Alkenyl-Substituted Succinic Acid,” ACI Materials Journal, May-June 2001, pages 224-232.] Neither of the Allyn, Jr., et al. publications provides structural details of the disclosed composition nor teachings as to synthesis of the disclosed composition.
Despite efforts to date, a need remains for treatments, materials and processes that can reduce and/or eliminate vapor transmission, e.g., moisture transmission, through porous structures such as concrete-containing structures in an efficient, reliable and cost-effective manner. These and other needs are advantageously satisfied by the disclosed treatment systems and methods.